Engine-generator speed control



Aug. 20, 1957 w. E. MCFARLAND 2,803,757

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ENGINE-GENERATOR SPEED CONTROL Filed Nov. 8, 1954 6 Shee ts-Sheet s g 1am:

ENGINE-GENERATOR SPEED CGNTRGL William E. McFarland, Nntley, N. 1. Application November 8,1954, Serial No. 467,351

15 Claims. (Cl. 290-40) This invention deals with idling devices for internal combustion engines driving electric generators. More specifically, it relates to devices designated to limit the fuel to the engine at no load condition, so that operation thereof is significantly quieter and more economical under such conditions.

Small engine driven electric power plants, such as those for portable use and for various individual generating applications, are commonly designated as generating sets. With such units, load demand generally is intermittent, so that lowered speed must be enforced at times when there is no load, and various devices have been proposed and used to enforce such lowered speed during no-load periods. The engine in such units generally is equipped with a speed regulator system employing a centrifugal governor adapted to regulate the throttle so as to maintain a predetermined or normal load speed within sufiiciently close limits to regulate satisfactorily the voltage and frequency.

The most efiicient type of idling device so far proposed is based on the principle of providing an effective force which acts to limit the fuel supply to such an extent that the engine operates at a speed lower than normal load speed and, in such cases, the usual governor speed control system is made ineffective as long as the limiting force is effectively applied. An idling device of this type generally has a winding which, when energized, exerts a force to render ineffective the fuel limiting force or force means and thus allows restoration and maintenance of normal load speed operation under load. This winding is placed in series with the load generator and the load circuit so that, when the load circuit is closed by connection of an electrical appliance, the winding becomes energized.

Such a winding may be located in a transformer or in electrical or electro-mechanical relays, or simply in an electromagnet which directly motivates the fuel limiting element which, for example, may be a plunger acting upon a throttle to keep it closed to idling condition during the period when the electromagnet is not energized. In order to exert the necessary control upon the throttle, the winding must be sufficiently energized so that the plunger or the armature of a relay or other device will be operated to achieve the necessary limiting means-removal effect. Unfortunately, in the case of typical generator set applications, the initial connected load may be a small one having high electrical resistance and, due to the markedly loW voltage generated at idling speed, there is insufficient current flow through the winding to energize it sufficiently so as to enable it to exert this limiting means-removal effect, it being understood that the winding must be sufficiently coarse so that it does not become overheated by the efieet of full rated current flow when maximum load is connected to the circuit. Obviously, the effective ampere-turns of the Winding must be quite few in the case of initially connected loads of smaller size, resulting either in complete lack of response by the winding or need of unduly delicate and sensitive control apparatus.

atent Another serious defect with generator set idling devices applied to A. C. motors is that such motors draw a heavy current until they have reached a speed high enough to throw out the starting winding. In the case of conventional generator sets without idling devices, the unit runs at full speed when a motor is connected as a load and the starting surge may merely slow down the unit momentariiy, but running inertia will furnish the necessary restarting power. If an idling device is used, the load burden on the engine will be relatively small at the instant the load is switched on, as generated voltage will be low, but the load burden increases as acceleration progresses, and a point may be reached where the engine, at a stage of partial acceleration is too burdened to accelerate farther. Since the load motor may not then be able to throw out the starting winding, it would necessitate use of an unduly large and powerful generator set to adequately solve the problem. Hence it is highly desirable that, when an initial load is switched on, the flow of power be sufliciently restricted to unburden the engine until significant acceleration takes place. It is also highly desirable that the throttle be forced wide open at the time that actual delivery of normal power to the load takes place, so that there is no time-lag during which the engine is slowing down undesirably while waiting for the centrifugal governor to effect the necessary motion for fully opening the throttle, it being well known that such governors require a time-lag for effecting a major change in throttle position.

In application Serial Number 453,911, filed on September 2, 1954, by William E. McFarland, of which this application is a continuation-in-part, there is described a simple and practical idling device for generator sets employing an electromagnetic means having a coarse winding in series with the load circuit and generator, for removing the fuel-limiting means. The winding is directly actuated by energy derived from circuit flow which eliminates the complexity of electric relaying devices, electro-hydraulic units, or equivalent relaying devices.

in such structures as outlined in the aforesaid copending application, there is a lack of uniformity in the speed or rate of initial throttle opening, because the speed of action of the directly energized electromagnet is dependent upon the size of the initial load. When the initial load is large, the fuel limiting means is withdrawn too rapidly, the throttle springs open too quickly, thus tending to stall small engines. In the event this coarse Winding acts upon a relaying device, rather than by direct action, the rate of initial throttle opening may be uniform, but even this is not a desirable condition, because it is most desirable that the rate of throttle opening on connection of load be in accordance with the particular ability of the engine to absorb the widening throttle opening, which ability varies with temperature changes and other conditions.

The aforesaid faults of idling systems are corrected in the present invention which, broadly, embodies the following elements:

1. Fuel limiting means, independent of the speed governor system, which applies a force to hold a throttle closed, thus enforcing an idling speed under no-load condition.

2. A high resistance winding energizable by current flow through the load and adapted, when energized, to effect removal of the limiting means at initiation of load.

3. A low resistance winding in series with the load and load generator at least for the duration of the load, or other equivalent holding means adapted to hold the fuel limiting means in ineffective condition for the duration of the load.

4. Switching means actuable upon termination of load current flow and thereby adapted to connect the high resistence winding in series with the load and a generator, and also actuatable upon acceleration of the engine toward normal load speed and thereby being adapted to remove the high resistance winding from in-series relationship with the load.

5. During the period when the fuel limiting means is held in the ineffective position, the speed governor system is permitted to control the throttle (and thus the engine speed) in the normal manner.

The invention will be understood more readily by reference to the accompanying drawings in which Figure 1 illustrates diagrammatically an engine in idling condition and a speed control system according to the present invention, associated therewith, while Figure 2 depicts the same system at on-load condition. A similar system'connected to an auxiliary control throttle is shown in Figure 3, in idling position. Another modification of the present invention is shown in the idling condition in Figure 4 and in the on-load condition in Figure 5. Figure 4A depicts the system shown in Figure 4 with changes to reverse the manner in which the control forces are applied. Another embodiment of the invention in idling condition is presented in Figure 6. Figure 6A illustrates a further modification of the system depicted in Figure 6. Figures 7 and 8 illustrate the system of Figure 6 at two other different stages during the course of initial acceleration of the engine. A detailed side view of a lever fuel limiting device employed in the system shown in Figure 4, is illustrated in Figure 9, while Figure 10 is a detailed side view of a cam device coacting with a similar lever of the system presented in Figure 6. Figure 11 depicts a sectional view of an electromagnet employed in the fuel limiting means of the systems illustrated in Figures 4 and 6. Another and preferred modification of the present invention utilizing an electrical governor for the engine is shown in on-load condition in Figure 12. Figure 13 depicts a system according to the present invention wherein a different means is employed for holding ineffective the fuel limiting means. Similar numerals refer to similar parts in the various figures.

In the drawings, some of the circuits illustrated are spe cifically alternating current circuits, while others are not. Accordingly no attempt will be made herein to distinguish between resistance and impedance and, in general, the term resistance will be considered to include both effects.

Referring again to the drawings and particularly to Figure 1, numeral 1 represents an internal combustion engine such as a small gasoline engine, which is not portrayed completely in all details, but which is shown to have crankcase 2 and fuel intake pipe 20. Engine 1 is, connected to drive electric generator 3" which may be A. Cfor D. C.,1and which has a field 4 excited by exciter 8 shown to have its separate field 9". The invention herein disclosed is applicable to most types of small A. C. or D. C. generator sets, there being certain desirable expedients which may be adapted specifically to one of either type. However, the system depicted in Figure l is, selected so that it would be operable satisfactorily under either condition so as to simplify the explanation of the invention involved.

"Although other types of governors may be employed with engine 1, a conventional centrifugal governor 10 is generally indicated, but not shown. This governor has the usual governor lever or arm 11, the motion of which is adapted to regulate the fuel throttle valve 22 so as to closely regulate speed. The effect of the centrifugal mechanism of the governor (which would be disposed within the crankcase), in combination with governor loading spring 12, is to move governor arm 11 to the rightin the drawing when the predetermined speed setting is exceeded, and to move and eventually hold arm 11 to the leftward limit, determined by stop 14, when engine speed is below normal load speed. Adjustment screw 15 permits adjustment of the governed speed.

'Fuel intake pipe 29 connects carburetor 21 with the engine. Throttle valve 22 (hereinafter also referred to asijthe throttle), is mounted within intakeZQ on pivotpin 23 to which is fastened (outside of intake 20) throttle arm 24' designed to move interiorly disposed throttle 22. Although in most engines the throttle is mounted integrally with the carburetor, it is shown separately here for the sake of clarity.

An adjustable stop 25 is mounted on bracket 26 which, in turn, is mounted on intake 20. Stop 25 determines one limit of motion of throttle arm 24, thus providing a fixed limit of throttle closure, i. e. that limit which would provide sufiicient fuel to maintain a slow idling speed. Spring 27 is affixed to arm 24- and to bracket 26 and it exerts sufiicient pulling force only to move the throttle open, when it is unopposed, with reasonable rapidity against incidental friction and inertia.

A rigid wire link or rod 28 is swivelly connected to the upper end of governor arm 11 and is slidably disposed in an opening in flange 200 on the lower end of the throttle arm 24'. A small lockable ball or stop 29 is aflixed to link 28 in .a position between arm 11 and arm 24 to provide a thrust surface, so that When governor arm 11 moves rightwardly (in the drawing) it can effect closure of throttle 22 via ball 29 to regulate engine speed. Thus it may be seen that the engine speed regulating system is complete and operable without benefit of the idling device hereinafter described. As illustrated and described, the connection between governor arm 11 and throttle arm 24' is of a one-way yielding nature (described in further detail in said copending application Serial No. 453,911) permitting throttle 22 to be independently closed by application of a very light force and, aside from the action of the idling device to be described, the speed governing system described for Figure 1 will operate in the normal manner as ball 29 is continuously pressed against flange 200 of arm 24', in conjunction with the action of light acting spring 27. Thus, throttle arm 24' and governor arm 11 will move in unison as though conventionally connected by a rigid non-yielding link. The one-Way yielding linkage is employed to enable the fuel limiting means of the idling device (to be described) to act independently of the aforesaid speed governor system and, in the event the effect of said idling device is insufficient, to adequately close the throttle against the force Which may be exerted by governor arm 11.

An angle-shaped iron bracket or panel 32 is used for mounting the elements of the idling device, and it is afiixed to engine 1 by being clamped or bolted between intake pipe 20 and the engine proper. In practice, the idling control elements may be encased suitably as, for instance, in the usual control or switch box which contains receptacles and meters, but a mounting bracket such as 32 is one practical arrangement enabling clear illustration. Load circuit 60 is shown in bold lines. It leads from the upper terminal of load generator 3 to relay contacts 131 and 131 (to be, described), thence through winding 1 92 of electromagnet 1%. (to be described), thence through a load switch. 61, load 62, and to the lower terminal of generator 3". Load 62 is indicated as a variable resistance, whereas in practice it may be one single appliance connected intermittently or, more usually, a series or variety of diflferent sized appliances, each having its own switch or plug, so that the switching on of any appliances will close the load circuit.

The electromagnet designated generally by numeral 169 has iron end supports 1101 and 101 which, with iron bracket 32, provide a return magnetic circuit. A coarse winding 102 of sufliciently low resistance to remain in series with the generator and load for the duration of the load, is employed and it becomes energized when load circuit flows, but variably according to the size of current flow as determined by the size of the connected load. A plunger 103, has one end slidable within a tube (not shown) on which winding 102 is wound. Iron stop 1M serves to limit the travel of plunger 103 and enables magnetic locking of said plunger in its inward or withdrawn position when winding 192 is energizedtoatleast a smallextent.

A small non-magnetic wire or rod 105 is fastened to the heretofore free end of plunger 103 and passes through a small bore in stop 104, and the free end of rod 105 ex tends out of the right end of electromagnet 100.

A chain or other collapsible link 106 connects the free end of rod 105 with throttle arm 24', thus serving as a one-way yielding linkage so that, if plunger 103 is well extended (through de-energization of winding 102), throttle arm 24 will be pulled to its most leftward position as determined by stop 25 (idling position), so that only sufficient fuel for maintaining idling speed still can be supplied to the engine. Yet, when plunger 103 is held in withdrawn position by energized winding 102, chain 106 will collapse and the engine will be left under control of its speed governor system.

A long lever 110 is pivoted on a stud 111 which is attached to bracket 32. Spring 113 (similar to spring 43 in Figure 9) urges lever 110 to be drawn in a clockwise direction, while the other end of spring 113 is anchored in one of the tension adjustment holes 114. The mounting details of lever 110 may be the same as those shown for lever 40 in Figure 9. The lower end of lever 110 is swivelly connected to the left end of plunger 103 so that lever and plunger move together, and the normal effect and force of spring 113 is to maintain plunger 103 extended (when the plunger is not held by energized wind ing 102 or through energization of winding 122), in spite of the opposition of the speed governor system which, in the present case, would consist only of the pull of spring 27. It is apparent, therefore, that the force of spring 113 is greater than that of spring 27.

Thus far, there has been described an operatively com plete idling device already previously disclosed. Aside from adequate energization of coarse winding 102, fuel flow is limited to idling speed requirement (when plunger 103 is in extended position) and the speed governor system is incapable of increasing fuel flow to obtain operation at load speed. In order for the fuel-limiting effect to be appropriately applied and relieved, a sufiicient motivating force is necessary, and electrically controlled hydraulic or other means have been employed to provide such force. Such a system has the disadvantage that control response is inherently weak or entirely ineffective when the initial load circuit current flow is small, with the additional disadvantage that engine acceleration is laborious when the initial load is a heavy motor. In the structure so far described, if the initial load is a very large one, plunger 103 will pull in quickly in spite of the fact that generated voltage is then low, and throttle 22 may be opened so rapidly as to cause improper engine response. However, once acceleration to normal speed has occurred and plunger 103 has been engaged with stop 104, operation will continue on a normally governed and satisfac tory basis even though load circuit current flow becomes small. It is thus seen that a coarse winding such as winding 102 is suited for locking or holding in ineffective position an idling device of the type just described, once the powering of the load is normally under Way. But it is highly unsuitable for such operation under conditions encountered at initiation of load as well as other conditions which will be apparent from the subsequent discussion.

According to this invention, such objections and disadvantages have been overcome by use of features incorporating an independent electromagnet 120 having end brackets 121 and 121 mounted on main bracket 32. Electromagnet 120 has a winding 122 having a resistance value higher than that of winding 102 of electromagnet 100, the wire size of winding 122 being selected to derive adequate energization when winding 122 is in series with the load and a driven generator in the system and, in general, the wire size being such as to provide a value of resistance higher than that of the normal or usual connected loads, and preferably higher than that of the smaliest used load applied to the system. It will be understood that the resistance of a given appliance does not have a strictly definite value, since the resistance of unstarted motors and unheated lamp filaments, for example, are much lower than when they are operating normally and, with respect to winding 122, it is the cold resistance which is used as the guide because the appliance will be in this condition when energization of winding 122 occurs, which condition will tend to remain during the short period when winding 122 is energized. The resistance of winding 122, however, preferably is not too greatly higher than that of normal loads, as beyond this point the available energy from winding 122 will become progressively less. Actually, the high resistance of winding 122 is high in the sense that it is impractical to leave it in the load circuit for duration of the load for the reason that it would become excessively overheated or it would adversely affect the load line voltage.

Electromagnet is provided with plunger 123 and the usual iron stop 124. Plunger 123 has an enlarged flat engaging end 125 disposed so that it can engage or bear against the extreme end 201 of lever 110 so that lever 201 may be swung rightwardly during inward or withdrawing motion of plunger 123 caused by energization of winding 122, but plunger 123 may extend independently of lever 201 since engaging end 125 is extended leftwardly. A spring 126 surrounds the extended portion of plunger 123 and it exerts a force such that, when plunger 123 is fully extended, spring 126 will resist only lightly the inward motion but will offer gradually increasing resistance as the plunger moves inwardly. A small red or wire 127 is fastened to plunger 123 and extends loosely through a small bore in stop 124. Rod 127 has a bent end serving as a stop whereby further outward extension of plunger 123 is suitably limited.

A switching relay 130 is provided having a normally open pair of contacts 131 and 131 and an operating coil 132 in shunt with exciter generator 8 through means of wires 133 and 134. A wire 135 connects contact 131 with one terminal of winding 122 and the other terminal is connected to load circuit 60 at a point so that, when contacts 131 and 131 are closed, the terminals of winding 122 will be short-circuited, and when these contacts are open, winding 122 will be disposed in series with generator 3 and load 62 if switch 61 is closed. It is necessary that winding 122 be removed from the load circuit at a specific time, so the aforesaid by-pass switching in Figure 1 is provided to accomplish this. For the purposes of this invention, winding 122 is considered to be removed or disconnected from the load circuit when its terminals are short-circuited. The positions of the various elements depicted in Figure 1 are those of the idling condition under no load. Plungers 103 and 123 are both fully extended and spring 113 is effective in hold ing throttle 22 at the position for idling speed fuel requirement, the governor arm 11 being disposed in leftward position under the low speed condition. Relay has its contacts 131 and 131 open since only the low generated voltage of idling speed is applied to the relay operating coil Winding 132.

On closing load switch 61, to throw in the load, winding 122 will be suitably energized so that plunger 123 will be moved quickly partway inwardly. Since the resistance of winding 122 preferably is higher than that of any usual load, the degree or" initial load current flow is primarily the result of the idling speed voltage with respect to the resistance of Winding 122, almost as though winding 122 were in shunt with generator 3". The energization obtained is uniformly and adequately dependable and suificient to overcome the effect of spring 113 via engagement 125 with lever end 201. But initially, due to the nature of spring 126, plunger 123 is pulled only partly inwardly, which condition enables at least some opening of throttle by the governor speed control system, thereby enabling smooth and sure acceleration. As acceleration progresses, the increasing voltage of generator 3" enables continuance of the inwardmotion of plunger 123, the desirable and achievable Condition being that the fuel limiting effect (resulting in the pull on chain 106) is gradually and entirely over-come by the time engine 1 reaches load speed when throttle 22 is practically wide open and the'engine is gaining speed rapidly. The resistance of winding 122 generally will be such that the wattage load o'ngenerator 3" at this stage is insignificant as a burden on the engine.

As load speed is approached, plunger 103 preferably will have been brought to'meet step 104. Winding 192 has been energized to'some slight extent by the afores'aid load circuit current flow, but it has so few-turns of Wire in its winding thatits effect on plunger 103 is still negligible as compared with the effect on plunger 123 by Winding 122. If the resistance of winding 122 is quite high, as specified herein, it has the effect of reducing initial load current flow to a point well below the smallest usual initial load current flow when only the usual coarse winding is employed for the idling device, but most of the energy available from load circuit current flow now is concentrated in'winding 122, whereas when only a coarse winding (such as 1&2) is in series with the load circuit, practically all of the energy of the load circuit current flow is lost, being dissipated in the load appliance rather than utilized usefully in controlling the removal of the effect of the fuel limiting means. The comparative efliciency of the usual coarse winding and the auxiliary high resistance winding outlined here can be more readily understood by considering that with respect to quite a small load, the coarse winding when used alone would be able to extract but a fraction of one percent of the energy of the initial load circuit current flow, whereas an auxiliary high resistance winding, as outlined herein, would be able to extract in the neighborhood of over fifty percent of the energy of a somewhat reduced initial load circuit current flow. if the resistance of winding 122 is lower than thatherein specified, then winding M32 will contribute in greater measure to the initial effort, but it has been found that the progress of initial throttle opening isbest controlled and most uniform when substantially the entire initial motivation is effected by the high resistance winding 122.

It is preferable that only as the engine approaches full speed with throttle 22 well open will relay 130 have its coil 132 sufficiently energized to disconnect effectively winding 122 from in-series relation with generator 3" and load 62. When this takes place, voltage will be normal and normal load power current will flow, and the usual surge of current for starting the load will occur. Plunger 1&3 will complete any slight necessary travel to meet stop 1% and, thereafter, small energization of winding 192 will enable locking of plunger 1113 to core Hi4 with little or no air gap except as may be provided to assure release of the plunger at the end of the load period. Governor arm 11 will move rightwardly upon reaching full load speed to thereafter (via ball 29) regulate the fuel supply for load speed operation, there now being sufficient slack in chain 1% to permit throttle arm 24 to be moved freely to required positions. Plunger 123, upon de-energization of winding 122, will have extended and will be without any further effect. At termination of all load current flow, winding 192 has no energization and spring 113 will apply its effect to limit fuel supply to idling speed requirement, which operation will move plunger 1% to extended position. Upon sufficient deceleration toward idling speed, contacts 131 and 131 will open, thus placing winding again in series with the generator and load circuit in preparation for the next load.

It is the function of relay 130 to respond so that winding 122 is placed in the series circuit only after termination of on-load period, but prior'to connection of the next load, and to reverse the switching operation only after substantial acceleration toward load speed. Any

mechanically or electrically operated mechanismwhich can be adapted to respond and perform with-suitable accuracy may be employed. It is most suitable that the relay mechanism be accurately responsive to change in engine speed, opening contacts 131 and 131 say midway in the course of deceleration, and closing the contacts with dependability at or near full speed. In practice, any good voltage relay with its coilin shunt with a D. C. generating system would provide a simple and economical mechanism as the switching means, with suitably accurate response to change in engine speed. Relay 13tl may be of a relatively close differential type, in which case it would open its contacts upon a very moderate reduction in engine speed. In such case, if the initial load is a heavy motor, and engine momentum is inadequate to start the load rolling on the first attempt and the engine loses a certain amount of speed as a result, relay will open its contacts, thus unburdening the engine for fresh acceleration, and this cycle will be repeated until the load is turning freely enough to be started.

For certain applications, it is practical that relay 130 be designed to by-pass winding 122 at such a point when engine acceleration is merely well under way. But the more nearly the acceleration is completed when relay 130 performs the by-pass switching, the better is the motorstarting ability of the generator set, and the initial actual power flow in the load circuit is most nearly normal to assure ability of coarse winding 102 to establish the locking or holding operation at the high speed status.

Figure 2 illustrates the unit depicted in Figure 1 at the advanced state of acceleration wherein plungers 103 and 123 are pulled way inward, throttle 22 nearing its maximum opening, but with relay contacts 131 and 131 and governor arm 11 still remaining at idling speed positions.

Figure 3 illustrates typically the application of the idling device system of Fig. l in the condition wherein a supplementary throttle 22 is required for imposing the fuel limitation. In many 2-cycle gasoline engines, particu' larl it is not only permissible to use a separate control throttle to impose the idling effect, but the primary governed throttle is of such type or is so located in the crankcase that it is impractical to make connection with the idling device. In Figure 3, the speed regulating system including governor 10, non-yielding rigid link 28' and associated throttle valve 22 may be considered as a typical internal combustion engine governor speed control regardless of whether it is located internally or externally with respect to the engine.

In Figure 3, the separate control throttle 22 is pivoted on pin 23 to which is attached throttle arm 24 to which is attached chain 106, so that the normal effect of this idling system is to hold throttle 22' closed to the limit determined by stop 25. Spring 27 is effective in holding open throttle 22 when the normal effect of the idling device is relieved upon connection of a load. It will be noted that there is no difference between the general operation of the system in Figures 1 and 3 where the use of two throttles does not interfere with proper low-speed carburetion, because control throttle 22 will be of no effect for periods when loads are being served.

From the aforesaid, it is apparent that, in one respect, this invention involves use of an engine burden-relieving resistance automatically inserted in circuit with the load after the conclusion of one load, and before the inception of the next, permitting unburdened acceleration, after which the resistance is automatically removed to establish normal connection of generator to the load. In another "aspect, the invention involves use of an auxiliary energyderiving winding temporarily in circuit with the load for obtaining sensitive control upon removal of the fuel limiting means. Specifically, the auxiliary winding of higher resistance than the normal loads, together with a switching device, simultaneously accomplishes the two objectives. A further aspect involves means to limit the progress of initial throttle opening proportionately to the engines'ability to make use of the widening throttle opening during the load initiation period. In the foregoing figures, governor ltl, link 28, spring 27, link 166, lever 110 (which is connected through plunger 1493) and spring 113 comprise an adjustable system for selectively controlling the fuel intake to effect required changes in engine speed. Plungers 102 and 123, spring 126, and engaging end 125 comprise an armature system acting on the adjustable system to establish or set the phases of adjustment of the adjustable system.

Another modification of the present invention, depicted in Figure 4, employs the same general operation as that in Figure 1, except for expedients for combining elements in the idling device, for extending efficiency, and uses a circuit which, in general, is more particularly suited for a D. C. load generator 3. It also shows slightly different details in the interconnections between governor, throttle and idling device. Generator is driven by the engine and is a permanent magnet alternator having rotor 6 carrying the magnet fields, and a stationary stator or armature 7. Generator 5 is shown as utilized only for supplying a certain control current of small wattage but, if desired, it may be large enough to utilize its current for excitation or otherwise.

The idling device in Figure 4 includes an electromagnet indicated generally as 36. It has iron end brackets 31 and 31 carried by the angle-shaped main mounting bracket 32, all of which form the return magnetic circuit. The electromagnet has the usual tube 33 surrounding which is a front Winding 34- and a rear winding 35. An iron plunger or armature 36 has a portion thereof contained Within tube 33 and is slidable therein. A fixed iron core 37 also is disposed within the tube and may be slightly longer than rear winding 35. An insulating separator 38 indicates the space occupied by each of the windings 34 and 35. Details of electromagnet 30 are shown in Figure 11. Considering energization of winding 35 alone, it will be noted that its characteristics are not those of a plunger electromagnet. It is designed so that if plunger 36 is once positioned very close to core 37, it then would be magnetically locked in position through energization of winding 35. Considering only the energization of winding 34 alone, ele-ctromagnet 30 is a plunger electromagnet of ordinary efficiency, capable of bringing plunger 36 inwardly into withdrawn position to make contact with core 37.

A metal lever 4%! (Figure 4) is pivotally mounted on a stud 41 attached to bracket 32, the arrangement being shown more clearly in Figure 9. Lever 40 has a flange 42 and is pivotally connected at point 203 with the extended end of plunger 36, enabling both plunger and lever to move together. Spring 43 has one end 43 anchored in one of the adjustment holes 44 and its other end 43' bears on lever it to maintain plunger 36 in extended position when the windings are not holding the plunger in withdrawn position. A rigid link 45 of tempered wire or other suitable material has its right end swivelly attached to throttle arm 24 and its left end slidably supported in an opening in flange 42. A loop 46 is formed in link 45 and surrounds governor arm 11 to serve as a one-way yielding linkage and as a thrust projection against which governor arm 11 may exert a rightward thrust to close throttle 22. A sharp bend 47 is provided in link 4-5 serving as a step whereby spring 43 may press flange 42 thereagainst in a manner to close the throttle to a predetermined (idling) limit, thus serving as the fuel limiting means independent of the engine speed governor control system. Free end 48 of link 45 is of sulfi'cient length to enable retention of link 45 in flange 42.

Throttle 22 is normally closed lightly to a predetermined idling limit determined by stop 25 as spring 43 has a greater force than governing system spring 27. Energization of winding 34 will relieve the throttle-closing effect by pulling lever 40 leftwardly, so that the governing system is made capable of providing fuel requirement for load speed operation.

- A switching relay 50 is mounted on bracket 32 and has an operating coil Winding 51, one normally-closed pair of contacts 52 and 52' and one normally open pair of contacts 53 and 53' and wires 54 and 55 connecting coil 51 in shunt with generator 3. Relay 56 will reverse the contact positions shown in Figure 4 at such time as when the voltage of generator 3 approaches peak-speed voltage, and will again reverse contact positions when voltage of generator 3 has fallen in response to partial deceleration of engine 1 toward idling speed.

The normal load power circuit is indicated by bold line 60, beginning from the upper terminal of generator 3 through electromagnet Winding 35, relay contacts 53 and 53', load switch 61, load 62, and the lower generator terminal. Wire 63 connects one terminal of permanent magnet generator 5 with relay contact 52. Contact 52' is connected with one end of coil 34 by wire 64. The opposite end of coil 34 is connected by wire 65 with that portion of the load circuit 60 which leads from contact 53 and through load switch 61 and load 62 to the lower terminal of the generator. Thus, with contacts 52 and 52' closed and a load switch 61 closed, a circuit is active from one terminal of permanent magnet generator 5, through winding 34, load appliance 62, returning to generator 5. At this switching status, contacts 53 and 53 are open and load generator 3 is disconnected from the load circuit.

As depicted in Figure 4, the engine is in idling condition. By closing a switch 61, the described circuit will assure energization of electromagnet 30 to draw in plunger 36 enabling spring 27 to open throttle 22. The function of winding 34 is the same as the function of the high resistance winding 122 in Figure 1, and the mode of selecting the resistance of winding 34 is on the same general basis. Electromagnet 30 has not been provided with any spring which would be the equivalent of spring 126 of Figure 1 for retarding opening of throttle 22 for the reason that such a spring inthe system of Figure 4 would make it excessively difiicult to maintain plunger 36 locked magnetically in the withdrawn position. By making winding 34 of suitably high resistance, the normal throttle closing effect of spring 43 is overcome in a positive and uniform manner, and the engine accelerates unburdened toward load speed.

Initial energization of the load circuit upon closing of switch 61 occurs from the output of permanent magnet generator 5. This offers a number of advantages. The higher the voltage available for energizing the initial load circuit, the greater is the available energization of winding 34 to extend the range of initial response to still smaller load size. Permanent magnet generator 6 may be designed to have at least as high a normal voltage as that of load generator 3 and, in addition, since it has permanent magnet fields, it suffers a lesser collapse of voltage at idling speed. It is also an advantage that the initial load circuit, which includes winding 34, be energized with alternating current. In the event generated D. C. current is used for energizing winding 34, there may he need for a protective device against overheating damage as might result if, through some fault of operation, energization of the initial circuit were continued; whereas in the case of using A. C. current, coil 34 is suitably protected by the fact that, as acceleration progresses and higher voltage is applied to winding 34, frequency also is increasing rapidly, particularly as plunger 36 nears stop 37, providing sufficient reactance to limit current flow and preventing rapid overheating of winding 34. Use of a permanent magnet alternator for energization of the initial circuit, together with the high sensitivity of winding 34 will, in general, permit idling operation of the engine at the lowest speed at which an engine will reasonably operate, and do so with positive control of shift to load speed, whereas with conventional generators there is a certain low speed at which the field strength will break down, and no significant voltage will be produced 11 thereafter until a suificient engine acceleration is reached to build up the field again.

As previouslyoutlined, closing of load switch 61"eifects energization of winding 34, so that plunger 36 will be pulled into withdrawn position to make contact with core 37, causing lever 40 to move leftwardly to the position as shown in Figure 5, thus allowing throttle 22 to be opened to the maximum extent by spring 27 of the governor system, and acceleration will continue at full throttle until governor arm 11 moves rightwardly. Then, relay 50 will pull in properly as full speed is approached as its operating coil 51 is receiving increasing voltage from generator 3. This action opens contacts52 and 52 (as in Figure to interrupt the initial circuit, and quickly thereafter closes contacts 53 and 53" to restore the normal powercircuit. Load 62 is served the initial surge current and this, together with continued normal load current flow, effects energization of coarse winding 35 sufliciently to hold plunger 36 in withdrawn position for the duration of even a small load current flow. At least before the engine speed has appreciably exceeded normal speed, governor arm 11 will move rightwardly as necessary, bearing against the right end of loop 46 in link 45, and thereafter, with cooperation of spring 27, will regulate throttle position as necessary, the left end 48 of link 45 sliding freely through flange 42 as the link moves.

On-load status of the assembly in Figure 4is shown in Figure 5. Here, the fuel limiting means has been rendered ineffective and held so by action of solenoid and normal load speed governing is in effect. Throttle 22 is partly open as for an average load, plunger 36 is magnetically held in fixed position by winding (since winding 34 has been removed by the contacts of switching relay 59) and relay contacts 53 and 53' are closed. At termination of all load, plunger 36 is freed by de-energization of winding 37, whereupon spring 43 is effective for applying the fuel limiting effect on throttle 22 toenforce idling condition.

In the foregoing Figures 4, 4A and 5, governor it), link m 28 and 210, spring 27 or 211, lever 40 or 40, and spring 43 comprise an adjustable system for selectively controlling the fuel intake to effect required changes in engine speed. Plunger 36 comprises an armature system acting on the adjustable system to establish or set the phase of adjustment of the adjustable system.

Figure 6 depicts a system generally similar to that outlined in Figure 4 but employs elements to correct deficiencies with respect to control of the rate of throttle opening. In addition, Figure 6 embodies certain highly efficient circuit arrangements utilizable when the load generator is an A. C. generator. In this case, numeral 3 represents an A. C. generator excited by the D. C. armature system 8, field 9 being shown as common to both A. C. and D. C. generating systems, as is common practice in small plants. Electromagnet 30 is of the same general design as the one illustrated in Figure 4. The usual tube 33 supports a suitably high resistance front winding 34 and a rear winding 35' to be described.

Lever 46 of Figure 6 is pivotally mounted on stud 41, the mounting detail being shown in Figure 9. Lever 40 also has an outwardly extending flange 42, and the lower end 203 of lever 46 connects to plunger 36. Spring 43 urges lever 40 to move counterclockwise. As specifically shown in Figure 6, with spring 43 stronger than spring 27, throttle arm 24 will be held at the fixed limit determined by stop 25. If the one-way yielding linkage between governor arm 11 and throttle arm 24 were eliminated, as by making loop 46 sufficiently short that all movement of arm 11 must be transmitted'to arm 24, then, in order for arm 24 to be normally pressing stop 25, spring 43 would be required to be of greater strength than governor loading spring 12. This, in turn, would require sufficiently powerful motive means incorporated in the idling device to relieve and hold off the force of spring 43 during load speed operation. The requirement for greater motive power in turn tends to make the energy which can be derived from load circuit flow (both with respect to the high resistance and low resistance windings) inadequate as motive power to pull in plunger 36, and necessitates relaying devices which introduce complications and greatly increase manufacturing costs. Yet, it is to be noted that the system outlined in Figure 6 is operative as an idling device if the loop 46 were shortened as described. The normal effect of spring 43 will be to oppose the governor loading spring 12 so that governor It) can now govern only at a certain reduced speed below load speed, the degree of reduction being dependent upon the strength of spring 43, and the permissible strength of spring 43 will, in turn, be dependent upon the available power from the electromagnetic means specified. And, if stop 25 now is sufliciently readjusted, it may still be acting as a limit, and the idling speed will be less than load speed. Thus, in a sense, the one-way yielding connection of governor with throttle is not a necessary element in the present invention.

In the practice of this invention, however, it is necessary to provide switching means adapted to appropriately insert and remove the high resistance winding with respect to its position in series with the load circuit. This makes it practically necessary that the idling speed be sulficiently lower than load speed so that there is sufficient range to obtain dependable response from an ordinary and practical type of relay to operate the switching. Accordingly this invention is applicable primarily to enforcing the condition of idling speed greatly lower than load speed, whereas in the prior art, accomplishment of fully low idling speeds has not been achieved. As far as the one- Way yielding connection between governor and primary throttle is concerned, it is a secondary consideration here involving one of the methods for achieving speed governor control of the engine when the fuel limiting means does not enforce idling condition upon the throttle.

Relay 50 having operating coil 51 and normally-open pair of contacts 56 and 56' has coil 51' connected in shunt with exciter armature 8 by wires 54 and 55'. Relay 50' is designed so that when voltage of exciter 8 has risen to or near its normal value for the load speed, the relay will pull in its armature to close contacts 56 and 56, and when this voltage has fallen significantly, such as during deceleration, the relay will drop out to open contacts 56 and 56.

The load power circuit 60 is shown by a bold line. Starting from the upper terminal of generator 3', it leads first through winding 71 (to be described), then through relay contacts 56 and 56', through load switch 61 and load 62, thence to the lower terminal of generator 3. The circuit for initial engine acceleration is effective when contacts 56 and 56 are open, and proceeds from the upper terminal of generator 3' through a portion of load circuit 60', through winding 34, thence through line 67, again following load circuit 60' through switch 61 and load 62 to the opposite generator terminal. It will be noted, with respect to Figure 6, that the dilference between the circuit for acceleration and that for load power is merely the short-circuiting of the terminals of winding 34 so that the winding is by-passed. This is a simple and desirable switching arrangement not applicable to all of the modifications herein presented.

A current transformer indicated generally as is employed, deriving current from flow in load circuit 60' and includes primary winding 71, secondary winding 72, and core 73. Current from secondary 72 passes through selenium rectifier 74 or other equivalent rectifying means, and through wires 75 and 76 to the rear electromagnet winding 35'. Condenser 77 is optional and, if used, is connected across wires 75 and 76 and'will tend to smooth the ripple in the rectified current and somewhat increase rectified voltage. The design and proportions of transformer 70 are unconventional in view of the requirement that is as nearly uniform as possible regardless of how much or how little current is passing through primary winding 71. This is because practical types of rectifiers of the selenium type are usefully efficient only when the A. C. input to the rectifier is of a voltage that is at least a reasonable fraction of the rated voltage of the rectifier. In general, transformer 7th should have a slender, high permeability core with short turns of wire over as great a portion of the core length as possible for primary winding 71. The high permeability core permits efficiency from the transformer when load current flow is small, but the core becomes substantially saturated at relatively light load conditions, placing a practical limit on the voltage output of the transformer. Likewise, the saturated transformer can introduce only a low maximum of reactance in the load circuit, so that the voltage regulation to the load 62 is not noticeably affected.

In the case of Figures 1 and 4, coarse windings M2 and 35, respectively, were described to be in series with the load circuit for the duration of powering of the load, at least, and through the energization of said windings, the enforceable idling means was held in ineffective position. Windings 102 and 35 were incorporated in electromagnets. In the case of Figure 6, however, the coarse primary winding 71 is the equivalent of the coarse windings of Figures 1 and 4, in that it derives the necessary control energy from load current flow for holding the enforceable fuel limiting (idling) means ineffective, as will be described.

A cam device indicated generally as 80, bears against a cam roller 81 mounted on lever 40. Mounting details of the cam device are shown in Figure 10. Cam arm 85 is pivotally mounted on stud 82 which, in turn, is mounted on bracket 32. Spring 83 urges the cam arm to move in a counterclockwise direction. One end of spring 83 is anchored in one of the holes 34 in bracket 32. On arm 85 is an adjustable plate 86. When the positions of the elements are as shown in Figure 6, the cam device effect is substantially neutral, but when plunger 36 completes a certain portion of its withdrawal motion as in Figure 7, cam roller 81 will bear against plate 86 tending to halt further inward movement of plunger 36, and throttle 22 will have been opened only to a relatively small degree at this stage.

The positions of the elements depicted in Figure 6 are those of idling position (without load). Governor arm 11 is disposed leftwardly and throttle 22 is closed by force of spring 443. Relay contacts 56 and 56' are open so that when switch 61 is closed, there will. be a small current flow through winding 34 which itself represents the principal element of resistance in the circuit and thus determines the extent of initial flow. The energization afforded winding 34 at idling speed voltage is sufficient to move plunger 36 inwardly until roller 81 bears against cam plate 86 as shown in Figure 7. In this manner, the fuel limiting means is in part made ineffective. Spring 27 will immediately open throttle 22 to a propor tionate extent and engine 1 will begin acceleration, the rapidity of which at this stage is dependent upon Whether the engine is relatively cold or Well-warmed, or whether it is adversely aifected by oil-fouling from long idling. Regardless of the particular engine condition, there will be no misfire or stalling at the initial stage of throttle opening. Only when certain acceleration takes place and the engine is ready for wider throttle, will the energization of winding 34 be sufficient to draw plunger 36 inwardly, thus displacing cam arm 85 as shown in Figure 8 and, by action of spring 27, throttle 22 will open fully to accomplish rapid acceleration.

On approaching full speed with the engine effectively unburdened, relay will close its contacts 56 and 56 to short-circuit winding 34, thereby establishing the normal power circuit. The normal degree of load current flow will then occur, and the energization of winding 35' is required to make it effective in engaging plunger 36 tohold spring 43 from exerting its fuel limitingefifcch There are several considerations which make it relatively difficult for winding 35' to accomplish the engagement. The tendency of spring 43 is to immediately start moving the plunger to fuel limiting position. A certain instant is required for the A. C. energization of winding 34 to break down, and likewise, a certain instant is required for the D. C. energization of winding 35' to build up after normal load current flow begins. Also, the current flowing in coil 34 during the breaking down of its energization after short-circuiting may be adverse polarity to the energization of winding 35', so that plunger 36 may, for an instant, oppose core 37. At the instant that the shortcircuiting of winding 34 occurs with positions of elements as shown in Figure 8, spring 27 is exerting a certain small pressure through link 45 on lever 40 to partially offset the effect of spring 43 tending to extend plunger 36. Also, the effect of cam device now may be neutral, or cam plate 86 may even be adjusted so that the effect of the cam device is also to partially oppose spring 43, so that momentarily there may be a little or no force urging plunger 36 outwardly. There is, therefore, time for Winding 35' to build up energization for magnetically locking the plunger inwardly even though the load appliance is very small. Soon after engagement of plunger 36 and when core 37 is properly magnetized, governor arm 11 will move rightwardly, removing the slight pressure of spring 27 on arm 4%), and it will he noted that cam plate 86 can be at such an angle that there would be only sufficient force applied to plunger 36 to move it outwardly from contactwith core 37 at termination of load circuit current flow. Cam device 80 therefore is arranged not only to retard initially the tendency toward wider throttle position until acceleration is under way, but also to enable maintenance of the ineffective position of the fuel limiting or idling means with the least possible electrical energy. i

It may be noted also that if one of the windings 34 and 35' of electromagnet 30 were short-circuited, and A. C. energization supplied to the other winding, electromagnet 30 would represent a transformer with a shortcircuited secondary tending to cripple or eliminate the ability of core 37 to hold plunger 36. Therefore, it is impractical in this particular circuit and electromagnet to utilize a coarse winding for winding 35' in series with the load circuit and in addition, the arrangement of current transformer and rectifier for energizing winding 35', as described, is a more eflicient arrangement magnetically. Furthermore, it is practical to utilize the output of current transformer 7 0 for operating a relay. Such a relay arrangement is illustrated by Figure 6A which is similar to Figure 6 except for the inclusion of a relay 78. In Figure 6A, transformer secondary winding 72 is connected through rectifier 74 to the operating winding 78' of relay 7 8. Relay 78 thus will be operatively energized whenever there is a flow of load current through load circuit 60' which circuit includes primary winding 71. In turn, contacts 73 of relay 78 will close on initiation of load circuit current flow and remain closed for the duration of load flow thus assuring that electromagnet winding 35' is energized for the duration of load circuit current flow as would also be the case in Figure 6. Winding 35' in Figure 6A is connected with exciter generator 8 through a circuit which includes wires 54', 79 and 79' and contacts 73". Upon termination of all load circuit current flow in Figure 6, spring 43 will move lever 40 to extend plunger 36 into fuel limiting position, thus closing throttle 22 for idling speed operation and, upon partial deceleration, relay 50 will again open its contacts 56 and 56'.

A still different modification of the invention is shown in Figure 12, and is particularly applied to the general condition wherein a relaying device is employed as the controlling element of the idling means. Figure 12 also serves to illustrate use of the present invention under the condition where the 'fuel limiting means for enforcing idling conditions is applied and removed by electrical adjustment of an electrical governor. While electromagnetic governors are equivalent to the centrifugal governors of the prior described figures and may be substituted without change in the plan of the idling control, it is practical in the case of electromagnetic governing to arrange the system so that the governor is normally overenergized, which makes the governor incapable of providing fuel for load speed.

In Figure 12, load generator 3" may be A. C. or D. C. and has its field 4 separately excited by exciter 8" which has its own field 9". A load circuit 60 is shown by the bold line, beginning from the upper terminal of generator 3", passing through relay winding 172 and a pair of relay contacts 181 and 181 (to be described), thence through load switch 61 and load 62, and then to the lower generator terminal. An angle-shaped mounting panel or bracket 14-0 is clamped between intake and engine 1. Supported on bracket 140 is an electromagnet indicated generally as 150 which, together with loading spring 151 comprise an electromagnetic speed governor for the engine. Governor loading spring 151 is connected at one end to throttle arm 24 and at the other end to an adjustment 152 affixed to carburetor 21. Governor 150 has iron end supports 153 and 153, a conventional plunger 154, and a core 155. Link 156 connects the extending end of plunger 154 with throttle arm 24. Loading spring 151 is necessarily considered an element of governor 150. 'l

The left end of plunger 154 is prevented by collar 157 from coming into close proximity with core 155, as the core is used merely to flatten out the pull curve of the plunger, rather than to engage or hold the plunger. Governor 150 has coil winding 160 which is connected by wires 161 and 162 with exciter generator 8". Resistor 163 is in series with the circuit. When resistor 163 is so connected in series, governor 150 will regulate the throttle to supply the fuel requirement for normal load speed within suitably close limits. Energization of winding 160 will rise and fall in accordance with variation of voltage from exciter generator 8", which voltage, in turn, will rise and fall rather accurately in proportion to any change in engine speed, since the exciter generator 8 is not subject to a variable load.

Figure 12 illustrates the system under load speed operation. Switch 61 is closed, plunger 154 is in intermediate position of its travel range, and throttle 22 is partially open. A current relay generally indicated as 170 and havin armature 170' is provided with contacts 171 and 1'71 which, when normally closed, by-pass resistance 163. Relay 171) has a coarse winding 172 of such low resistance that it may remain in series with generator 3 and load 62 for the duration of the connected load, the winding being representative of the usual coarse series winding in electrically responsive idling devices. Relay 1711 also includes a high resistance winding 173 which should be selected to be higher in resistance than that of the load carried, as this winding serves the same general functions as the high resistance windings described for the previous figures. These windings may be arranged concentrically or in tandem, as desired, and the arrangement shown in Figure 12 is merely illustrative of the fact that there are two windings in the one relay device. If generator 3" is an A. C. machine, relay 170 will be required to respond to low frequency current, and the relay design will be selected for elficiency at low frequency, such as using a plunger type of relay.

A single pole double throw relay 180 is provided with center contact 131-and normally-open contact 181 and normally-closed contact 1811", together with an operating coil 182 connected in shunt with exciter generator 3" by means of wires 1% and 184. As in the preceding figures, this relay will respond to voltage-from exciter S" to pull in its an nature l dl as s peed reaches nearly normal load speed, and to drop out after significant deceleration at a value still above that of full deceleration. Wire 185 connects one terminal of high resistance winding 173 with contact 151". In the positions depicted, load circuit flow is through coarse relay winding 172, which derives energiZation to maintain relay contacts 171 and 171' in open position, while contact 181 is closed with contact 181'. Upon opening of load switch 61, there is no further energization of coarse winding 172, so relay contacts 171 and 171 must close. Resistance 163 now is by-passed and the full voltage of exciter generator 8" is applied to winding 160. Resistor 163 may be of several times higher value than that of winding 160 so, temporarily, winding 160 will be hi hly over-energized to draw plunger 154 inward to the maximum and thus enforce closing of the throttle to the limit determined by stop 25 and, in this way, serving as the fuel limiting means.

Provided only that the adjustment of stop 25 is sulficient to prevent too slow an idling speed, winding 160 will remain sufficiently energized by the idling speed voltage of generator 8 to hold throttle 22 closed to the (idling) limit. If adjustment screw 25 is backed too much, a point will be reached where governor takes up the governing of the throttle, but this is desirably avoided as the governor will not be suited for smooth operation at the slow idling speed suited to generator plants employing this invention. Aside from energization of relay 171 through load circuit current flow, the fuel limiting or idling means of Figure 12 is normally efiective to limit fuel how for idling speed requirement. And, in the present case, the efiective idling means is merely the normally-closed relay contacts 171 and 171 which provide over-energization of the electric governor.

Upon adequate deceleration toward idling speed, decrease in' energization of relay coil 182 will cause center contact 181 to open with respect to contact 181, and to close immediately with contact 181". Coarse winding 172 now is out of the load circuit, and high resistance winding 173 is in series with a potential load and generator 3". On next closing an appliance switch 61, winding 173 is energized, causing relay 170 to pull in and open contacts 171 and 171. Engine 1 is unburdened through benefit of the high resistance of winding 173 and winding is momentarily under-energized, so throttle 22 will be immediately driven fully open by loading spring 151 where it will remain until load is taken on.

As engine 1 approaches full speed, relay 1841 will ac complish its switching, opening contact 181 to disconnect high resistance winding 1'73 from the load circuit, and closing contact 181 to connect coarse winding 172 into the load circuit. Current flow in the load circuit is entirely interrupted for a brief instant during the aforesaid switching operation, but the initial load surge will, if necessary, quickly accomplish reopening of contacts 171 and 171 if they have tended to close as a result of the interruption for switching. Energization of winding 172 will hold the opened condition of contacts 171 and 171 for the duration of the load circuit current flow.

In Figure 12, governor 151i, loading spring 151, link 156, and resistor 163 comprise an adjustable system for selectively controlling the fuel intake to effect required changes in engine speed. Relay armature and contacts 171 and 171' comprise an armature system acting on the adjustable system to establish or set the phases of adjustment of the adjustable system.

As is apparent from the foregoing description relative to Figure 12, by use of the high resistance winding it is possible to accomplish the unburdening of the engine during acceleration, to obtain the fully wide throttle opening for taking on the load, and to obtain sensitive control enabling response to small loads. In the foregoing figures, both the low and high resistance windings acted directly to restrain the effect of the fuel limiting means and, while there would be no sacrifice of the benefits derived if the energization obtained by the low resistan-ce winding is used to effect control through a relay device, it is clear that the energization derived by the high resistance winding is more effectively employed when it is direct, rather than when it acts through a relay, to provide controlled progress of initial throttle opening which is so badly needed for the attainment of acceleration.

In the foregoing figures, a low resistance winding has been utilized, in series with the load generator and load during the period of load, as the basic element for hol ing load speed effective for the duration of load, that is, from the completion of engine acceleration to the switching off of the load. In the broader aspects, the present invention represents a system for bringing a generating plant back to load speed upon initial connection of load, and may be practiced in combination with any practical device or arrangement which is designed to hold the plant at load speed statue once the acceleration phase is completed. While the use of a low resistance winding as the controlling element, is suitably simple and fully automatic, there are conditions where other means may be preferred.

One means which may be employed for obtaining idling control of a generator set is the use of a remote control wire; that is, one or more wires in addition to the load circuit wires, and running from the plant to a convenient switch near the load appliance, or connected directly to the appliance through some form of coincidental switching whereby, in a single switching operation, the appliance is connected or disconnected and at the same time the proper switching is provided for the remote control wire. Where the appliances are of such nature that coincidental switching is practical, the idling control operation is fully automatic, and there is even certain benefit in that the usual voltage drop through the low resistance winding is eliminated.

Heretofore, when a remote control wire arrangement has been employed, it was the entire basis of the idling control. In the case of the present invention, the initial engine acceleration occurs directly as a result of current flow through the load, and the remote control wire is employed only to hold the fuel limiting means ineffective for the duration of load, and then establish the fuel limiting means to be effective again when the load is disconnected. Thus, the function of a remote control wire, in combination with the present invention, is the same as the function of the low resistances winding of the previous figures.

Figure 13 shows one preferred arrangement utilizing :a remote control wire, with a form of coincidental switching which is adaptable to manually-operated load appliances or adaptable to automatic appliances such as refrigerating machines. Figure 13 includes load generator 3", which may be A. C. or D. C., having field 4", excited by exciter generator 8 with its own field 9". Governor, throttle and fuel limiting means are identical with those of Figure 4, the lever 40 being urged rightwardly to maintain throttle 24 closed to idling position. Relay 50' is as described for Figure 6, its operating coil 51 being disposed in shunt with exciter generator 8" through wires 54' and 55', and these contacts will close when the plant acceler ates to or near load speed, and will open at a midpoint of plant deceleration from load speed.

An electromagnet indicated generally as 250 includes end brackets 251 and 251 attached to main bracket 32, and the electromagnet has a high resistance winding 252 of a character as described for previous figures, and has a plunger 253 which is attached to the lower end of lever 40 to move in unison with the lever. On plunger 253 is a disc 254 serving as an element in a latching arrangement to be described.

An electromagnetic latch, indicated generally as 255 is mounted on the main bracket 32, and has an operating winding 256, a plunger 257, a plunger spring 258. Attached to the extending end of plunger 257 is latch 255. A small extension rod 261 limits the downward motion of the plunger 257. The strength of spring 258 is such that plunger 257 will remain fully downward, as illustrated, except when the operating winding 256 is highly energized.

The load circuit 60, starting from the upper terminal of generator 3, passes through contacts 56 and 56' when closed, thence through load 62, load switch 61' when closed with its leftward contact, thence to the lower terminal of generator 3". If contacts 56 and 56 are open, the load circuit will include the high resistance winding 252 and wire 67.

Load switch 61' is shown as a single pole double throw switch. When in leftward position, the load circuit is closed, but when the switch is rightward as illustrated, a circuit is completed from the lower terminal of generator 3", thence through remote control wire 259, thence through operating winding 256 of the magnetic latch, and thence through wires 260 and 60, to the upper terminal of load generator 3". With load switch in the illustrated position the operating winding 256 is in shunt with load generator 3", but this winding is not sufiiciently energized to raise plunger 257 so long as idling speed is in effect.

The illustrated position is that of idling, with contacts 56 and 56 open. Upon throwing load switch 61' leftward to close the load circuit, high resistance wind ing 252 is energized and will draw in its plunger 253, which will move lever 40 leftward to permit throttle ad vance and acceleration with the engine unburdened. As plunger 253 nears the end of its inward travel, disc 254 will strike latch 255 momentarily, raising latch 255 to gether with attached plunger 257, and when disc 254 has arrived at the dotted line position indicated, latch 255 and attached plunger 257 will again drop to their illustrated position, but plunger 257 now is locked in the inward position. Thus lever 40 is locked at its leftward position and operation must continue at load speed until latch 255 again is raised.

Upon suflicient acceleration, contacts 56 and 56' will close, and normal power delivery to the load will be in effect. To terminate the period of load, switch 61' will be thrown over to its rightward position which, as described, places the operating winding 256 of the latch ing device in shunt with load generator 3 which at this moment is providing the full voltage of load speed. The resulting energization of winding 256 is sufiicient to raise plunger 257 and attached latch 255, and spring 43 will immediately move lever 40 rightward, plunger 253 out ward, and simultaneously close the throttle to idling posi tion. The reduced speed of idling Will cause sufficient loss of energization in operating winding 256 that plunger 257 and attached latch 255 will drop again to the lowest position as illustrated, in readiness to lock the operation at load speed upon the next phase of acceleration.

It will be understood that there are numerous variations in remote control wires and associated switching which will provide control effect equivalent to that of Figure 13.

It will be observed also that the high resistance Winding in Figure 4-A makes ineffective the fuel limiting means which includes spring 211. Although it does not remove the effect of said spring, it accomplishes the same result by overcoming its effect by the stronger force of the winding when the latter is energized.

As is apparent from Figure 4-A, when compared with Figure 4, the forces in the idling mechanism may be reversed and, if proper changes in the other components are made, the resulting effect is still the same. Figure 4-A represents the system shown in Figure 4 with the exception that changes are made due to the reverse manner in which the control forces are applied. Governor arm 11 is shown in Figure 4A as connected by one form of a one way yielding linkage 28 with throttle arm 24. Lever 40' is connected to throttle arm 24 by means of tightly-wound spring 210 which is shown with a few chain links 212 attached so as to better indicate that the con nection from lever 49' to throttle arm 24, for the engine idling condition illustrated, is in slack condition. Throttle closing spring 211 attached to throttle arm 24 is unopposed and will hold the throttle closed. Lever 40' is disposed rightwardly since electromagnet 30 is de-energized. Tightly wound spring 2l0 cannot contract any further, and there is sufiicient slack in the one way-yielding connection so that spring 211 can close the throttle to the idling limit. Upon application of load, lever 40 will be moved and held at the leftward position which will expand throttle opening spring 219 and thereby exert a throttle opening force which is stronger than the eifect of throttle closing spring 211, so that, for the duration of the load, the throttle will be held advanced to the limit imposed by speed governor arm 11.

Even though the aforesaid discussion has been directed to the application of the present invention to spark-ignition engines, it is to be understood that the present invention is equally applicable to diesel engines by making the necessary changes and adaptations familiar to those skilled in the art.

It will be further apparent from the aforesaid disclosure that the present invention has provided a much-needed idling control for engine-driven generators, giving results unattainable by prior art systems.

I claim:

1. In a speed selection system for an internal combustion engine driving at least one generator including a load generator supplying current through a load circuit to a load, said engine having a controllable fuel intake means and an adjustable system, including an engine governor, said adjustable system being selectively adjustable for controlling said fuel intake means to effect a uniform governed load speed at one phase of adjustment and effect a substantially lowered idling speed at another phase of adjustment, said speed selection system including an armature system constructed and arranged to act on said adjustable system in a manner whereby the action of said armature system upon energization thereof establishes said phase of adjustment effecting the uniform governed engine loadv speed, and, when in position of deenergization thereof, sets said phase of adjustment effecting a substantially lowered idling speed, the improvement consisting of the hereinafter-specified electromagnetic means for maintaining said armature system in energized position for the period from initiation to termination of load circuit current flow, said latter means comprising a high resistance winding connectable in, and disconnectable from, the load circuit by the hereinafterspecified switching means, and constructed and arranged to energize said armature system in effecting said established phase upon connection in the load circuit and at initiation of load circuit current flow, holding means operating only during the period of load circuit current flow and constructed and arranged to hold said armature system to maintain said adjustable system in said established phase for the continuation of load circuit current flow, and switching means mechanically independent of said armature system and constructed and arranged to connect said high resistance winding in series with the load circuit at least by the time a load is initially connected in the load circuit and to disconnect said high resistance winding from the load circuit upon acceleration of the engine toward load speed.

In a speed selection system for an internal combustion engine driving at least one generator including a load generator supplying current through a load circuit to a load, said engine having a controllable fuel intake means and an adjustable system, including an engine governor, said adjustable system being selectively adjustable for controlling said fuel intake means to effect a uniform governed load speed at one phase of adjustment and effect a substantially lowered idling speed at another phase of adjustment, said speed selection system including an armature system constructed and arranged to act on said adjustable system in a manner whereby the action of said armature system, upon energization thereof, establishes said phase of adjustment effecting the uniform governed engine load speed, and, upon de-energization thereof, sets said phase of adjustment effecting a substantially lowered idling speed, the improvement consisting of the hereinafter-specified electromagnetic means for maintaining said armature system energized for the period from initiation to termination of load circuit current flow, said means comprising a high resistance winding connectable in, and disconnectable from, the load circuit by the hereinafter-specified switching means, and constructed and arranged to energize said armature system in effecting said established phase upon connection in the load circuit and at initiation of load circuit current flow, a low resistance winding connected in the load circuit and constructed and arranged, upon disconnection of said high resistance winding by said switching means, to hold energized said armature system to maintain said adjustable system in said established phase for the continuation of load circuit current flow, and switching means mechanically independent of said armature system and constructed and arranged to connect said high resistance winding in series with the load circuit at least by the time a load is initially connected in the load circuit and to disconnect said high resistance winding from the load circuit upon acceleration of the engine toward load speed.

3. A speed selection system according to claim 2, in which the high resistance winding is permanently connected in. series with the load generator and the load circuit and in which said switching means is arranged to disconnect said high resistance Winding upon engine acceleration by the short-circuiting of said winding.

4. A speed selection system according to claim 3, in which one generator driven by the engine is a D. C. generator, and in which the switching means is an electromagnetic switching relay having normally-open contacts connected across said high resistance winding to shortcircuit said winding upon closing of said contacts, and havingan operating coil in shunt with said D. C. generator, said switching relay being constructed and arranged to close said contacts upon substantial increase of voltage of said D. C. generator resulting from substantial acceleration of the engine toward governed load speed.

5. A speed selection system according to claim 2 in which the load generator is an A. C. generator and in which the said electromagnetic means includes an additional winding constructed and arranged to hold energized said armature system for the continuation of load circuit current flow, said electromagnetic means also including a current transformer having a primary winding serving as said low resistance winding and having a secondary winding, said electromagnetic means also including a rectifier connected between said second winding and said additional winding.

6. A speed selection system according to claim 5 in which said high resistance winding, said additional winding and the armature of said armature system comprise one electromagnet, and in which said high resistance winding is permanently connected in series with said load generator and the load circuit, and in which said switching means is arranged to disconnect said high resistance winding upon engine acceleration by the short-circuiting of said winding.

7. A speed selection system according to claim 6 in which said one electromagnet is a plunger electromagnet, and in which said armature system includes a springactuated fuel limiting means normally maintaining said fuel intake means in position to effect a substantially lowered idling speed during the de-energized period of said armature system.

8. Aspeed selection system according to claim 2 in which the high resistance. winding has a resistance higher thanthat of the usual load.

9," A speed selection system according to claim 8 in 21' which the high resistance winding has a resistance higher than that of the smallest usual load.

10. A speed selection system according to claim 9 in which the engine drives a permanent magnet generator in addition to the load generator, and in which the generated voltage of said permanent-magnet generator at the lowered idling speed is higher than that generated by said load generator, and in which said switching means connects said permanent-magnet generator and said high resistance winding in series with the load circuit at least by the time a load is initially connected in the load circuit and disconnects said high resistance winding and said generator from the load circuit upon acceleration toward load speed and at the same time connects the load generator and the low resistance winding in series with the load circuit.

11. A speed selection system according to claim 2 in which the controllable fuel intake means includes a throttle, and in which said adjustable system includes a mechanical engine governor constructed and arranged to regulate said throttle for uniform governed load speed, and in which said armature system includes a spring actuated fuel limiting means normally maintaining said throttle in position to effect a substantially lowered idling speed during the deenergization period of said armature system, and in which said armature system, when energized from the initiation to termination of load circuit current flow, relieves the eifect of said spring actuated means, thereby rendering the governor effective to regulate said throttle for uniform governed load speed operation.

12. A speed selection system according to claim 11, which includes an obstruction means acting on said springactuated fuel limiting means and constructed and arranged ato prevent its energized armature from fully relieving the effect of said spring actuated means until partial acceleration from the lowered speed toward the governed load speed has occurred, whereupon said armature is sufficiently energized by increasing current flow through said high resistance winding to overcome said obstruction means to complete the established phase for governed load speed operation.

13. A speed selection system according to claim 12 in which said obstruction means is a cam constructed and arranged to obstruct the action of the energized armature only after the force of said spring-actuated means has been partially relieved, and only after the speed governor has advanced the throttle to a predetermined extent.

14. A speed selection system according to claim 2 in which said adjustable system includes electromagnetic means and an energization circuit therefor, said latter electromagnetic means being constructed and arranged to be selectively adjustable by switching operation for controlling said fuel intake means to effect a uniform governed load speed at one phase of adjustment, and effect a substantially lowered idling speed at another phase of adjustment, and in which said armature system, when energized, is arranged to effect a switching operation to act on said latter electromagnetic means to establish said phase of adjustment effecting the uniform governed engine load speed and, when de-energized, effect a reverse switching operation to set said phase of adjustment effecting a substantially lowered idling speed.

15. A speed selection system according to claim 14 in which said latter electromagnetic means is an electromagnetic governor energized by generated current from a generator driven by the engine, switching contacts arranged to elfect a decrease or increase in energization of said governor, adjusting said governor, respectively, for governed load speed or for a lowered idling speed, and in which the armature of said armature system is a relay armature constructed and arranged to operate said switching contacts in a manner to decrease the energization of said governor from the initiation to the termination of load circuit current flow.

References Cited in the file of this patent UNITED STATES PATENTS 1,792,241 Ray Feb. 10, 1931 1,991,074 Blankenbuehler Feb. 12, 1935 2,242,072 Holslag May 13, 1941 2,396,176 Hobart Mar. 5, 1946 2,488,171 Campbell Nov. 15, 1949 

